The invention relates to a device for preventing the unintentional restarting of motors or machines, it being possible to control the supply of energy to the motor or to the machine by means of a control valve with a mechanically adjustable control element and it being possible to connect the control valve non-detachably to the motor or to the machine.
In electrical engineering, restarting preventers are known which prevent machines and/or motors being unintentionally restarted when the power supply is restored after a power failure. The supply of power is continuously interrupted in the event of a power failure and can only be switched on again by releasing or disconnection which is intentionally carried out by the operator.
DE 100 12 419-A discloses a pneumatically acting throttle valve for controlling the energy to a pneumatically operated motor. The throttle valve has a manually activated and rotatable lever for controlling the rate of air flow to the air motor. The throttle valve is non-detachably connected to the motor and to the machine. In order to activate the lever the first time, it must be released with a release latch. Once it is released, the lever will remain in the last position if the air pressure is interrupted. When the air pressure is restored, the motor and the machine can thus restart with the flow of air which was set before the air pressure was interrupted. Particularly with heavy and high-speed machines, it is not possible to rule out a situation in which the operator is placed in danger by the unintentional restarting of the machine.
Taking the prior art as a starting point, the object of the invention is to specify a device for preventing unintentional restarting, which device prevents the operator being placed in danger by the unintentional restarting of the machine, even in the case of pneumatically operated machines.
The foregoing object is achieved by means of a device for preventing unintentional restarting of motors or machines, it being possible to control the supply of energy to the motor or to the machine by means of a control valve with a mechanically adjustable control element and it being possible to connect the control valve non-detachably to the motor or to the machine, the energy for the motor being generated by means of compressed air, and a pneumatic piston, to which the primary air pressure prevailing upstream of the motor and upstream of the control valve can be applied, being arranged as a restarting inhibitor between the control valve and the motor, and a connecting line being arranged between the motor and the piston in order to apply the primary air pressure.
It is advantageous that the supply of energy to the motor can be controlled in the simplest way possible with an extremely compact device. This is achieved in that the mechanically adjustable control valve is embodied as a throttle valve which is loaded with a spring and operated with the primary pressure.
It is also advantageous that the supply of energy can be regulated as safely as possible and that the supply of energy cannot be switched on unintentionally. This is also achieved by virtue of the fact that the throttle valve has a release latch which has the purpose of releasing the mechanically adjustable control element and which can be activated manually.
It is also advantageous that in an emergency the energy supply can be interrupted in the simplest and most effective way possible. This is achieved in that an emergency shut-off device and a 3/2-way valve are provided in such a way that in an emergency the piston can be forcibly evacuated and can be reactivated again after the emergency only by mechanically releasing the emergency shut-off device.
The basic idea on which the invention is based is that an element which is frequently applied in the electronic control of electrical machines and motors is transferred by analogy to pneumatically driven machines. Locking functions in the air discharge lines of complex pneumatic or hydraulic control methods are known but not in the present simple form in the feed line to an air motor.